To enable achievement of a reduction in the thickness in a blade driving device that includes a driving member, and to enable a reduction in size of an installation area in a blade driving device that includes a driving member. The blade driving device 1 comprises a base member 2 that has an opening 2A, one or more blade members 3 that operate so as to advance into the opening 2A or withdraw from the opening 2A, and a driving member 4 that is supported on the base member 2 and that moves within a plane that is perpendicular to an optical axis that passes through the opening 2A, for driving the blade member, wherein the driving member 4 is disposed at a position that overlaps the blade member on the periphery of the opening 2A.